Conventionally, there has been known a refrigerating apparatus performing a refrigerating cycle, and the refrigerating apparatus has been widely used as a cooling machine for an air-conditioner which heats/cools indoor air, a food-stocking refrigerator, a freezer and a showcase. The refrigerating apparatus includes that of a type, as disclosed in WO98/45651, that performs both air-conditioning and cold-storage/freezing. The refrigerating apparatus of this type comprises a plurality of application-side heat exchangers such as an air-conditioning heat exchanger, a cold-storage heat exchanger and a freezing heat exchanger, and is installed in, for example, convenience stores.
The refrigerating apparatus of this type sometimes uses a plurality of combined compressors in order to widely vary the capacity of the compressor depending on the operation condition of the plurality of application-side heat exchangers. For example, the present applicant has been proposed an apparatus wherein three compressors including a compressor having variable capacity are combined to form a compression mechanism and, also, a four-way switch is provided on a suction side of the compression mechanism, so that the four-way selector valve is on/off controlled to switch the communication of four ports to allow the three compressors to be appropriately selectable for use for the air-conditioning side and cold-storage/freezing side (for example, Japanese Unexamined Patent Application No. 2001-233329). More specifically, in the apparatus, in addition to the four-way selector valve, four check valves are combined and used on the suction side of the compression mechanism, whereby the three compressors are operable in various combined patterns. For example, the all the three compressors can be used for the cold-storage/freezing side or, alternatively, the three compressors can be separated into two and one for use for the cold-storage/freezing side and the air-conditioning side, respectively.
-Problems to be Solved-
However, since the four-way switch valve and the four check valves are provided in a suction pipe, connection arrangements thereof are complex. In addition, when the cold-storage/freezing side or the air-conditioning side becomes deficient in ability, on/off control of the four-way switch valve is performed to switch the operation state of the compression mechanism. As a result, it is considered that the flow direction of refrigerant is reversed in each of the check valves on every switching, thereby causing noise (chattering noise).
Further, in the apparatus described above, the number of the check valves is as large as four. As such, when, for example, all the three compressors are used for the cold-storage/freezing side, the piping resistance of the suction pipe tends to increase to be relatively high. This can cause a pressure loss in the suction side, reducing the ability of the refrigerating apparatus.
The present invention has been devised in view of the above problems, and an object thereof is to provide a refrigerating apparatus wherein a switch valve, such as a four-way switch valve, and check valves are provided on the suction side of a compression mechanism formed from three compressors so as to switch operation states, thereby suppressing the generation of chattering noise in check valves and also preventing an ability from reducing due to a suction-side pressure loss.